1. Field of the Invention
The present invention relates to a sealed pushbutton switch, and particularly to a normally closed sealed pushbutton switch used in various electronic appliance.
2. Description of Related Art
A conventional sealed pushbutton switch is described in U.S. Pat. No. 6,459,057, which was issued on Oct. 1, 2002. The pushbutton switch is normally in a closed position, comprising a base, a plurality of fixed contacts assembled to the base, an insulative housing snapping onto the base, an actuator retained in the insulative housing and provided with a shaft and a head, a contact spring normally contactable of an inner edge of fixed contacts for establish an engagement between the contact spring and the fixed contacts, a wire compression spring abutting against a bottom of the head, and an O-ring mounted around the shaft. In operation, the actuator is pushed downwardly to thereby move the contact spring away from the fixed contacts for breaking the electrical connection between the fixed contacts. The pushbutton switch is then caused to be in an electrical opened position.
An electrical connection between the fixed contacts is established by an engagement between the contact spring and inner edges of the fixed contacts. However, the engagement between the contact spring and the fixed contacts is unreliable, not only because an out surface of the contact spring is discrete, but also because the inner edge of the fixed contact is narrow. Further more, the contact spring is moveably retained in the head of the actuator. As a result, the contact spring is hard to be availably driven by the actuator thus is hard to have a steady engagement with the fixed contacts.
Hence, an improved pushbutton switch is required to overcome the above-mentioned disadvantages of the related art.